Hitherto, conventional gaseous processes aimed at extending the shelf life of perishable materials have relied on modified atmosphere packaging (MAP) procedures. In such procedures, the oxygen gas atmosphere surrounding the substance is replaced with a food grade carbon dioxide and/or nitrogen atmosphere, and high barrier colaminate packaging is used to maintain the exclusion of oxygen from the package. The slight acidity produced by the carbonic acid which results from the exposure of the substance to carbon dioxide produces a fungicidal effect.
MAP processes have disadvantages, however. While it has been found that such procedures do extend the shelf life in respect of treated substances, the extension is limited and considerable costs are involved including the cost of the specialized colaminate film packaging.
In accordance with the present invention, there is provided a method and apparatus to effectively treat a perishable material with volatile substances by use of a carrier gas or gases to physically or chemically alter the material to preserve it against fungal or bacterial spoilage or other hazards thereby extending its shelf-life.